1. Field of the Invention
The present invention relates generally to the field of surgery. More particularly, the present invention relates to methods and apparatus for applying thermal energy to tissue during percutaneous surgery. Specifically, a preferred implementation of the present invention relates to an elongated catheter with a longitudinally split tip for directing thermal energy toward one side of the catheter during percutaneous surgery. The present invention thus relates to a surgical method and apparatus of the type that can be termed split tip.
2. Discussion of the Related Art
There has been previous medical experience with the use of surgical apparatus for delivery of thermal energy to tissue during percutaneous intervention. Prior art apparatus for applying thermal energy to tissue, sometimes called electrode tips, have been powered by radio frequency (RF) generators. For example, see U.S. Pat. Nos. 5,458,596; 5,514,130; and 5,569,242, the entire contents of which are hereby incorporated herein by reference as if fully set forth herein. U.S. Pat. Nos. 5,458,596; 5,514,130 and 5,569,242 disclose a controlled amount of thermal energy being delivered from a distal end of an electrode and an RF power source connected to a proximal end of the electrode.
However, a limitation of this technology has been that tissue that is to be treated by exposure to thermal energy is often close to tissue that should not be exposed to the thermal energy, resulting in potentially adverse affect to otherwise healthy tissue. Therefore, what is needed is a solution that permits thermal energy to be directed to the tissue to be treated without exposing nearby tissue to the thermal energy.
For example, intervertebral discs contain collagen that can be effectively treated with thermal energy to repair and/or reinforce the disc. However, there are spinal nerves on the outside of intervertebral discs next to the posterior and the posterior lateral areas of the discs. While the discs can be thermally treated, the spinal nerves should not be thermally treated.
Another example would be in brain surgery where a pathologic lesion could be treated by heating. However, the lesion would be surrounded by other very sensitive tissues that should not be treated.
Heretofore, the prior art has only provided general electrode tips. The electrode tips of the prior art do not have the capability of delivering heat to only one side of the tip. The electrode tips of the prior art have not been designed in a way that would allow the surgeon to place the electrode tip in between two layers of tissue and only provide the therapy to one of those two layers (i.e., to one side of the electrode tip). As a result of these limitations, the prior art tips run a risk of causing injury and necrosis to sensitive tissue. Heating and death of sensitive tissue (e.g., a spinal nerve root) can lead to loss of sensation and mechanical control of various parts of the body (e.g., the foot) or, as another example, loss of bowel control. In the brain the effects being risked could be very devastating.